linux-kernel - Re: [PATCH v4 0/6] landlock: Signal scoping support

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Message-ID: <ZuIynFIRt475uBP5@tahera-OptiPlex-5000>
Date: Wed, 11 Sep 2024 18:15:24 -0600
From: Tahera Fahimi <fahimitahera@...il.com>
To: Mickaël Salaün <mic@...ikod.net>
Cc: outreachy@...ts.linux.dev, gnoack@...gle.com, paul@...l-moore.com,
	jmorris@...ei.org, serge@...lyn.com,
	linux-security-module@...r.kernel.org, linux-kernel@...r.kernel.org,
	bjorn3_gh@...tonmail.com, jannh@...gle.com, netdev@...r.kernel.org
Subject: Re: [PATCH v4 0/6] landlock: Signal scoping support

On Wed, Sep 11, 2024 at 08:17:04PM +0200, Mickaël Salaün wrote:
> We should also have the same tests as for scoped_vs_unscoped variants.
Hi, 

Thanks for the review, I will add them soon.
> I renamed them from the abstract unix socket patch series, please take a
> look:
> https://git.kernel.org/pub/scm/linux/kernel/git/mic/linux.git/log/?h=next
Wonderful! Thank you :)

> I'll send more reviews tomorrow and I'll fix most of them in my -next
> branch (WIP), except for the hook_file_send_sigiotask tests and these
> scoped_vs_unscoped variants that you should resolve.
I will keep an eye on reviews. What parts of hook_file_send_sigiotask
would need changes?

> On Fri, Sep 06, 2024 at 03:30:02PM -0600, Tahera Fahimi wrote:
> > This patch series adds scoping mechanism for signals.
> > Closes: https://github.com/landlock-lsm/linux/issues/8
> > 
> > Problem
> > =======
> > 
> > A sandboxed process is currently not restricted from sending signals
> > (e.g. SIGKILL) to processes outside the sandbox since Landlock has no
> > restriction on signals(see more details in [1]).
> > 
> > A simple way to apply this restriction would be to scope signals the
> > same way abstract unix sockets are restricted.
> > 
> > [1]https://lore.kernel.org/all/20231023.ahphah4Wii4v@digikod.net/
> > 
> > Solution
> > ========
> > 
> > To solve this issue, we extend the "scoped" field in the Landlock
> > ruleset attribute structure by introducing "LANDLOCK_SCOPED_SIGNAL"
> > field to specify that a ruleset will deny sending any signals from
> > within the sandbox domain to its parent(i.e. any parent sandbox or
> > non-sandbox processes).
> > 
> > Example
> > =======
> > 
> > Create a sansboxed shell and pass the character "s" to LL_SCOPED:
> > LL_FD_RO=/ LL_FS_RW=. LL_SCOPED="s" ./sandboxer /bin/bash
> > Try to send a signal(like SIGTRAP) to a process ID <PID> through:
> > kill -SIGTRAP <PID>
> > The sandboxed process should not be able to send the signal.
> > 
> > Previous Versions
> > =================
> > v3:https://lore.kernel.org/all/cover.1723680305.git.fahimitahera@gmail.com/
> > v2:https://lore.kernel.org/all/cover.1722966592.git.fahimitahera@gmail.com/
> > v1:https://lore.kernel.org/all/cover.1720203255.git.fahimitahera@gmail.com/
> > 
> > Tahera Fahimi (6):
> >   landlock: Add signal scoping control
> >   selftest/landlock: Signal restriction tests
> >   selftest/landlock: Add signal_scoping_threads test
> >   selftest/landlock: Test file_send_sigiotask by sending out-of-bound
> >     message
> >   sample/landlock: Support sample for signal scoping restriction
> >   landlock: Document LANDLOCK_SCOPED_SIGNAL
> > 
> >  Documentation/userspace-api/landlock.rst      |  22 +-
> >  include/uapi/linux/landlock.h                 |   3 +
> >  samples/landlock/sandboxer.c                  |  17 +-
> >  security/landlock/fs.c                        |  17 +
> >  security/landlock/fs.h                        |   6 +
> >  security/landlock/limits.h                    |   2 +-
> >  security/landlock/task.c                      |  59 +++
> >  .../selftests/landlock/scoped_signal_test.c   | 371 ++++++++++++++++++
> >  .../testing/selftests/landlock/scoped_test.c  |   2 +-
> >  9 files changed, 486 insertions(+), 13 deletions(-)
> >  create mode 100644 tools/testing/selftests/landlock/scoped_signal_test.c
> > 
> > -- 
> > 2.34.1
> >